Can you define sinus bradycardia?

In brief:
Yes

A slow heart rate in which the electrical signal for each heartbeat originates from the sinus node (where it's supposed to originate).

Generally, in an adult, this means a heart rate of less than 60. But keep in mind you can have a heart rate less than 60 and still be okay. For example many good athletes, whose hearts are in great shape, have resting heart rates less than 60.

In brief:
Yes

A slow heart rate in which the electrical signal for each heartbeat originates from the sinus node (where it's supposed to originate).

Generally, in an adult, this means a heart rate of less than 60. But keep in mind you can have a heart rate less than 60 and still be okay. For example many good athletes, whose hearts are in great shape, have resting heart rates less than 60.
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